Cargo Handling and Vessel Stability
Vessel stability and cargo handling appear on every USCG OUPV and Master license exam. This guide covers every tested concept: the stability triangle (G, B, M), metacentric height, the GZ righting arm curve, free surface effect, angle of loll, weight shifts, trim calculations, draft mark reading, cargo securing, IMDG dangerous goods classifications, grain stability, and IMO intact stability criteria. Work through each section and you will be ready for every stability and cargo question on exam day.
Contents
1. Stability Fundamentals — G, B, and M
Vessel stability is the tendency of a vessel to return to its upright position after being heeled by an external force. Understanding stability requires knowing three key points and how they interact when the vessel is heeled.
The Stability Sequence When Heeled
- 1.The vessel heels. G does not move — it stays at the same point in the vessel because no weights have shifted.
- 2.The underwater volume changes shape. B shifts toward the low side (more volume is submerged on the low side).
- 3.A vertical line drawn upward through the new B position intersects the vessel's centerline at M (the metacenter).
- 4.If M is above G (positive GM), the buoyancy force acts through a point higher than the gravity force — a righting moment exists.
- 5.The horizontal distance between the lines of action of buoyancy and gravity is called GZ — the righting arm. GZ x displacement = righting moment.
The GM Formula
KB and BM come from hydrostatic tables (read from the stability booklet at the vessel's current displacement). KG is calculated by the master using the vessel's lightship KG plus the moments of all weights loaded. On the exam, you are typically given KM (read from the table) and asked to find KG or GM.
2. Metacentric Height (GM)
GM is the single most important stability parameter in day-to-day operation. It is the master's primary tool for assessing whether the vessel is safe to sail. The USCG exam tests GM extensively — both conceptually and through calculations.
Factors That Raise G (Reduce GM)
- Loading cargo high in the vessel (on deck, in high holds)
- Consuming ballast from double-bottom tanks (removes low weight)
- Free surface effect in partially filled tanks (virtual rise in G)
- Icing on superstructure, rigging, or deck cargo
- Adding topside weights (radar masts, electronic equipment, passengers on upper decks)
- Removing low ballast or shifting ballast from low to high tanks
Factors That Lower G (Increase GM)
- Loading ballast in double-bottom tanks
- Shifting cargo from high locations to lower holds
- Removing high cargo or deck cargo
- Filling tanks that were partially full (eliminating free surface)
- Discharging cargo from upper decks
The only way to change KM is to change displacement (change the draft). KM comes from the hull form. You cannot change the hull. But you CAN change KG by managing where weights are placed. The master's entire stability job is managing KG relative to KM to keep GM positive and adequate.
3. The GZ Righting Arm Curve
The GZ curve (also called the static stability curve or righting arm curve) plots the righting arm (GZ) in meters against the angle of heel in degrees. It is the most complete picture of a vessel's stability across its full range of motion. Every licensed officer must be able to read and interpret a GZ curve — the USCG exam tests this directly.
Reading the GZ Curve — Key Points
The slope of the GZ curve near zero equals GM / (57.3 degrees, the radian conversion). A steep initial slope means large positive GM and a stiff vessel. The tangent to the curve at 0° is proportional to GM — examiners use this to ask whether GM increased or decreased based on a modified curve.
The heel angle at which the righting arm reaches its peak value. Typically 30°–45° for well-designed vessels. IMO criteria require the maximum GZ to occur at an angle not less than 25°. Beyond this angle, the righting arm decreases — the vessel is losing its ability to self-right.
The area under the GZ curve between two angles represents the energy the vessel can absorb from waves and wind without capsizing. IMO requires the area under the GZ curve from 0° to 30° to be not less than 0.055 meter-radians, and from 0° to 40° (or the flooding angle if less) to be not less than 0.090 meter-radians. The area between 30° and 40° must not be less than 0.030 meter-radians.
The angle where GZ returns to zero on the descending side of the curve. Beyond the AVS, the vessel has negative righting moment and will capsize. A typical AVS for a well-designed vessel is 70°–120°. Vessels with AVS below 60° are considered to have limited range of stability. The exam may show two GZ curves and ask which vessel is safer in heavy weather — the one with the greater AVS and larger area under the curve.
Raising G (increasing KG) shifts the entire GZ curve downward. The initial slope decreases (less GM), the peak GZ value decreases, and the AVS decreases. If KG rises high enough, the initial GZ value goes negative — the vessel is now in the loll condition. This is why even a small increase in G from free surface effect can be critical on a vessel already operating with low positive GM.
| Criterion | Minimum Value |
|---|---|
| Area under GZ curve, 0° to 30° | ≥ 0.055 m·rad |
| Area under GZ curve, 0° to 40° (or flooding angle) | ≥ 0.090 m·rad |
| Area under GZ curve, 30° to 40° | ≥ 0.030 m·rad |
| Maximum GZ value | ≥ 0.20 m at angle ≥ 25° |
| Initial GM (corrected for free surface) | ≥ 0.15 m |
| Angle of maximum GZ | ≥ 25° |
4. Positive, Negative, and Neutral Stability
Positive Stability
M is above G. When heeled, the buoyant force (acting upward through B) and the gravitational force (acting downward through G) form a couple that tends to return the vessel to upright. GZ is positive at all angles up to the AVS.
Neutral Stability
M coincides exactly with G. GM equals zero. When heeled, the vessel stays at that angle — no righting moment and no capsizing moment. In practice, neutral stability is an unstable boundary condition that a vessel passes through on the way to negative stability.
Negative Stability
G is above M. GM is negative. When heeled even slightly, the vessel tends to heel further rather than return to upright. The vessel will settle at the angle of loll (where GZ momentarily equals zero again due to the rising B) or capsize if the heeling force exceeds the range of positive GZ.
The righting moment is in foot-tons or meter-tons. GZ is in feet or meters; displacement is in long tons or metric tons. A heavier vessel with the same GZ has a greater righting moment and is harder to capsize. A lighter vessel (in ballast, after cargo discharge) has less righting moment for the same GZ — this is why vessels in ballast condition are often more tender than vessels fully loaded.
5. List vs. Angle of Loll
This is one of the most heavily tested distinctions on the USCG exam. List and loll look similar from the outside (vessel heeling to one side) but have completely different causes and require opposite corrective actions. Applying the wrong correction to loll can sink the vessel.
List
Angle of Loll
6. Free Surface Effect and FSC Calculation
Free surface effect (FSE) is the loss of metacentric height caused by liquid sloshing in a partially filled tank or compartment. It is one of the leading causes of vessel capsizing and one of the most tested topics on the USCG exam. Understanding why it occurs and how to minimize it is essential.
Why Free Surface Reduces Stability
When a vessel heels, liquid in a slack tank shifts to the low side. This shifts the center of gravity of that liquid toward the low side, pulling the ship's overall G to the low side and upward. The result is a virtual rise in G — as if G had physically moved up, even though the weight of the liquid has not changed. This virtual rise in G reduces GM.
Key Facts About Free Surface Effect
7. Stiff vs. Tender Vessels
The terms stiff and tender describe a vessel's roll behavior and are directly related to GM. The exam tests both the definitions and the practical implications for safety and cargo.
Stiff Vessel — Large GM
Tender Vessel — Small GM
A master can estimate GM from the natural roll period without a stability calculation. Time the vessel's natural roll period (T) in seconds with a stopwatch. A short, rapid roll period indicates large GM (stiff). A long, slow period indicates small GM (tender). If the period is very long and the vessel hesitates before returning from each roll, the GM may be dangerously small or approaching zero.
8. Weight Shifts — Transverse, Longitudinal, Vertical
Shifting a weight already on board does not change displacement or draft. It changes only the position of G. Understanding how G moves in response to weight shifts is fundamental to stability and is heavily tested.
G Moves Toward the Shifted Weight
When a weight is moved from position A to position B, G moves from its original position toward B, along the line connecting the old and new positions of the weight. The formula for the shift of G is:
| Direction of Shift | Effect on G | Effect on GM | Effect on Trim/List |
|---|---|---|---|
| Weight Shifted Upward | G rises — GM decreases — stability reduced | No trim change | No list change if on centerline |
| Weight Shifted Downward | G lowers — GM increases — stability improved | No trim change | No list change if on centerline |
| Weight Shifted to Starboard | G moves to starboard — TCG off centerline | No trim change | Vessel lists to starboard |
| Weight Shifted Forward | G moves forward — LCG changes | Trim by the head increases | No list change |
| Weight Shifted Aft | G moves aft — LCG changes | Trim by the stern increases | No list change |
Transverse Center of Gravity (TCG) and List
The transverse center of gravity (TCG) is G's horizontal distance from the vessel's centerline. A vessel with TCG = 0 has no list (G is on the centerline). Any transverse shift of G produces list. The angle of list can be calculated for small angles as:
9. Adding and Removing Weight
Unlike weight shifts, adding or removing weight changes displacement, draft, and KM (from the hydrostatic tables). It also changes KG. The net effect on GM depends on the height at which the weight is added relative to the vessel's current KM.
Effect on KG When Adding Weight
A weight suspended from a crane or derrick acts as if it were located at the point of suspension (the crane hook or boom tip) — not at the weight's actual position. As soon as a lift is made, G rises to the height of the lifting point. This is why heavy lifts dramatically reduce stability during the lift, even if the final stowage position is low. The exam tests this: "A 20-ton weight is lifted from the deck using the vessel's derrick with a headblock height of 15 m above the keel — where does G act during the lift?" Answer: at the headblock (15 m above keel), regardless of where the weight actually is.
10. Trim, Draft Marks, and Displacement
Trim is the longitudinal inclination of the vessel — the difference between forward and aft drafts. A vessel trimmed by the stern (aft draft greater than forward draft) is the most common and preferred condition for most ships. Trim by the head (forward draft greater) reduces maneuverability and increases slamming in waves.
Reading Draft Marks
Draft marks are painted on the hull at the forward and aft perpendiculars (FP and AP). They show the depth of the keel below the waterline. On US vessels, draft marks are in feet and inches. On metric vessels, marks are in decimeters (tenths of a meter). The bottom of each number is the actual draft at that mark. To read a draft of 12'-6", you would see the number 12 with the waterline above it by 6 inches.
Trim Calculations
MCT1" = the moment (in foot-tons) required to change trim by 1 inch. MCTC = moment to change trim 1 cm. These values are read from the hydrostatic tables in the stability booklet at the vessel's current displacement.
Deadweight vs. Displacement
Total weight of the vessel including hull, machinery, crew, stores, fuel, ballast, and cargo. Equal to the weight of water displaced. Read from displacement tables using mean draft. Expressed in long tons (2,240 lb), short tons (2,000 lb), or metric tons (1,000 kg).
Weight of everything on board except the vessel itself — cargo, fuel, water, stores, crew and effects. DWT = Displacement - Lightship weight. This is the paying cargo capacity. A vessel's DWT determines how much cargo it can carry to its load line.
11. Stability Booklet and Intact Stability Criteria
Every vessel over a certain size must carry an approved Stability Booklet (also called Stability Data Book or Trim and Stability Booklet). This document is prepared by the shipbuilder or naval architect and approved by the flag state or classification society. It provides the data needed to calculate stability for any loading condition.
Contents of the Stability Booklet
IMO Intact Stability Criteria (IS Code 2008)
The International Code on Intact Stability (IS Code 2008) sets minimum stability criteria for vessels in international trade. National administrations (like the USCG) adopt these criteria through domestic regulations (46 CFR Subchapter S for US vessels). The criteria apply to all loading conditions from departure to arrival.
| Vessel Type | Minimum GM (corrected for FSC) |
|---|---|
| General cargo vessels (IS Code) | 0.15 m |
| Passenger vessels (subchapter H) | Variable — residual GM after damage |
| Grain carriers (Grain Code) | 0.30 m (after assumed grain shift) |
| Sailing vessels | Verified by GZ curve — initial GM not sole criterion |
| Fishing vessels (Torremolinos) | 0.35 m |
The maximum KG curve (or table) gives the highest allowable KG for each displacement that still meets all stability criteria simultaneously. The master calculates the vessel's actual KG for the proposed loading condition and verifies it is at or below the maximum KG at that displacement. If actual KG exceeds maximum KG, the loading plan must be revised — typically by shifting cargo lower, reducing deck cargo, or adding low ballast. This is the standard pre-departure stability check.
12. Damage Stability Basics
Damage stability refers to the vessel's ability to survive flooding of one or more compartments. SOLAS requires passenger vessels and certain cargo ships to demonstrate damage stability — meaning they remain afloat and upright with positive residual GM after a specified flooding scenario. The USCG exam tests the basic concepts of damage stability rather than complex calculations.
Treats the flooded compartment as open to the sea — the flooded volume is removed from the vessel's buoyancy. The remaining waterplane area and intact compartments must provide enough buoyancy to support the vessel. Used for regulatory damage stability calculations on passenger vessels.
Treats flooding as adding the weight of the ingressed water. The vessel sinks deeper and G changes. Simpler to calculate but less accurate at large heel angles. Often used for approximate damage stability assessments and on smaller vessels.
Vessels are divided into watertight compartments. The floodable length is the maximum length of compartment that can flood without sinking the vessel. A higher subdivision factor (less floodable length per compartment) provides greater damage resistance. Passenger vessels require higher subdivision standards than cargo vessels.
After flooding, the vessel must: (1) remain afloat with positive freeboard on the intact side; (2) have a residual positive GM; (3) not exceed maximum heel angles; (4) have a range of positive residual GZ of at least 15° beyond the equilibrium heel angle. Passenger ships must survive flooding of any single compartment; larger ships may need to survive two-compartment flooding.
Permeability (μ) is the fraction of a compartment volume that can actually be flooded (the rest is occupied by structure, machinery, or cargo). Empty cargo holds: μ = 0.95. Machinery spaces: μ = 0.85. Accommodation spaces: μ = 0.95. Stores: μ = 0.60. A fully flooded empty compartment uses nearly all its volume as added water; a machinery room has 15% of its volume occupied by engines, pumps, and structure.
13. Grain Cargo Stability
Bulk grain is one of the most hazardous cargoes for vessel stability. Unlike liquid in a tank, grain can shift when the vessel rolls — even just a few degrees — causing a permanent heel that can lead to capsize. The International Grain Code (incorporated into SOLAS Chapter VI) governs the carriage of bulk grain worldwide.
Why Grain Is Dangerous
- Grain is a granular solid that behaves somewhat like a liquid when subject to vibration or motion
- A full grain hold has a void space at the top (the grain surface is not perfectly flat)
- When the vessel rolls, grain on the high side can avalanche into the void, shifting the cargo permanently to the low side
- This is called grain shift — it creates a permanent list similar to a weight shift to the low side
- Grain shift is not corrected by rolling back — once shifted, the grain stays shifted
- Grain also settles during a voyage due to vibration, increasing void space and potential shift
International Grain Code — Key Requirements
- Angle of heel due to grain shift must not exceed 12 degrees
- Residual GM (after grain shift) must be at least 0.30 meters
- Net residual area of GZ curve from equilibrium angle to flooding angle must be at least 0.075 m·rad
Stowage factor (SF) is the volume (in cubic feet or cubic meters) occupied by one ton of cargo. For grain: wheat SF ≈ 47–50 ft³/ton; corn SF ≈ 48–52 ft³/ton; soybeans SF ≈ 50–52 ft³/ton. A lower SF means the grain is denser and takes up less volume per ton — fewer voids and less heeling potential. The examiner may ask you to calculate the weight of grain that can be loaded in a hold of known volume:
14. IMDG Code and Hazardous Materials
The International Maritime Dangerous Goods (IMDG) Code governs the transport of hazardous materials by sea. It is mandatory under SOLAS Chapter VII and incorporated into US law through 49 CFR and 46 CFR. The USCG exam tests IMDG Class definitions, segregation requirements, and documentation.
The Nine IMDG Hazard Classes
IMDG Segregation Requirements
Segregation prevents incompatible dangerous goods from coming into contact in the event of leakage, fire, or explosion. The four segregation categories define the minimum separation required:
IMDG Documentation Requirements
15. Cargo Securing — Lashing, Blocking, and Bracing
Cargo securing prevents cargo from shifting during the voyage. Shifted cargo raises the center of gravity, creates list, and in extreme cases causes capsize. The USCG exam tests the principles of cargo securing, the Cargo Securing Manual requirements, and lashing calculations.
Methods of Cargo Securing
Wire rope, chain, or webbing straps attached from the cargo to deck lashing points (pad eyes, sockets). Lashings restrain the cargo from sliding, tipping, or lifting. Safe Working Load (SWL) must exceed the forces calculated from ship motion.
Wooden blocks, beams, or proprietary frames wedged between cargo units and ship structures to prevent movement. Particularly effective for preventing sliding. Must be secured so they cannot become projectiles if cargo shifts.
Packing material (wood boards, mats, air bags) placed between cargo units and the ship's structure to: distribute weight evenly, prevent damage from contact, allow air circulation, and protect cargo from sweat and moisture.
Container Securing Hardware
Forces Acting on Cargo
The CSS Code (Code of Safe Practice for Cargo Stowage and Securing) provides methods to calculate the forces on cargo from ship motion. The accelerations depend on the ship's length, beam, block coefficient, metacentric height, and service area. The three primary forces are:
SOLAS VI/5.6 requires all vessels of 500 GT and above built after January 1, 1998 to carry an approved Cargo Securing Manual. The CSM must contain: inventory of all portable securing equipment (with SWL); location of fixed deck fittings and their SWL; securing arrangements for all types of cargo units the vessel regularly carries; instructions for maintaining and inspecting securing equipment. The CSM must be specific to the vessel — generic manuals are not acceptable. USCG Port State Control examiners inspect the CSM during vessel examinations.
16. Deck Cargo Rules
Deck cargo presents unique stability risks because it is loaded high in the vessel, raising G and reducing GM. Special rules and precautions apply to vessels carrying cargo on open decks.
Timber (lumber) carried on deck entitles the vessel to a reduced freeboard (timber load line) because the timber provides reserve buoyancy and reduces the risk of progressive flooding. However, timber also absorbs water during the voyage, increasing its weight and raising G. Stability calculations for timber vessels must account for water absorption (typically 10–15% weight increase). The Timber Load Line Convention and ILLC protocols apply. Timber must be secured with lashings rated for the expected sea conditions.
Containers on deck must be secured with twist locks, bridge fittings, and lashing rods per the CSM. Stack weights are limited by the structural capacity of the deck, the container corner post design load, and the stability requirements. High stacks of heavy containers dramatically raise G. Container vessels use ballast to compensate when stacking heavy containers high on deck.
Ice accumulation on deck cargo, rigging, and superstructure raises G and reduces freeboard. High-latitude and cold-weather routes require icing allowances in the stability calculation. The IS Code provides icing allowances: 30 kg/m² on exposed weather decks and 7.5 kg/m² on projected lateral area of the vessel above the waterline. Vessels in icing conditions must be prepared to remove ice and recheck stability. Icing has capsized numerous fishing vessels and smaller cargo ships.
The IS Code criteria include a weather criterion: the vessel must withstand the combined effect of beam wind pressure on the exposed lateral area plus rolling. The wind heeling lever (lw1) from a 26 m/s (50-knot) wind must be less than 0.5 × GZ at the static angle of heel due to that wind, with an area reserve requirement. This criterion is most demanding for vessels with large above-deck structures — ferries, ro-ro vessels, and container ships with high deck cargo.
The Load Line Convention (ICLL 1966) sets minimum freeboard requirements — the distance from the waterline to the freeboard deck. Load line marks on the hull show the maximum draft in various conditions: S (Summer), W (Winter), WNA (Winter North Atlantic), T (Tropical), F (Fresh Water), TF (Tropical Fresh Water). Loading beyond the applicable load line mark is a serious violation (46 CFR 42). Deck cargo that would submerge the load line mark is prohibited. The USCG exam tests the locations of load line marks and which mark applies in which zone and season.
17. Cargo Manifest and Documentation
Cargo documentation establishes what is on board, where it is stowed, and who is responsible. Proper documentation is required by USCG regulations, customs law, and international conventions. Missing or incorrect cargo documentation is a common PSC deficiency and exam topic.
Cargo Calculations — Loading Table Example
| Item | Weight (t) | KG (m) | Moment (t·m) |
|---|---|---|---|
| Lightship | 1,200 | 4.80 | 5,760 |
| Hold 1 cargo (lower) | 300 | 2.10 | 630 |
| Hold 2 cargo (lower) | 250 | 2.30 | 575 |
| Hold 3 cargo (upper) | 150 | 6.80 | 1,020 |
| Deck cargo | 80 | 9.20 | 736 |
| Fuel (double bottom) | 120 | 0.80 | 96 |
| Freshwater | 40 | 1.20 | 48 |
| Stores and crew | 20 | 5.00 | 100 |
| TOTAL | 2,160 | 8,965 |
18. Frequently Asked Questions
What is metacentric height (GM) and how does it affect vessel stability?
Metacentric height (GM) is the vertical distance from the center of gravity (G) to the metacenter (M). A positive GM means M is above G and the vessel is stable — it will return to upright after heeling. A negative GM means G is above M and the vessel is unstable. The exam formula is GM = KB + BM - KG. A large positive GM produces a stiff vessel with a short, snappy roll; a small positive GM produces a tender vessel with a slow, sluggish roll. Both extremes create problems: stiff vessels are uncomfortable and place stress on cargo and structures; tender vessels may not meet minimum stability criteria.
What is the difference between list and angle of loll?
List is a permanent heel to one side caused by an off-center transverse center of gravity (TCG). The vessel has positive GM but heels because G is not on the centerline. Correction: shift weight back to centerline. Angle of loll is caused by negative GM — the vessel's G is above M. The vessel heels to one side (or both sides alternately) and rests at an angle where the righting arm GZ equals zero. This is far more dangerous than list. The WRONG correction for loll is to move weight to the high side — this can cause catastrophic capsize. The correct action is to lower G: add low ballast, flood double-bottom tanks, or remove high weights.
How do you calculate free surface correction (FSC)?
Free surface correction (FSC) accounts for the virtual rise in G caused by liquid sloshing in partially filled tanks. Formula: FSC = (i x density of tank liquid) / (V x density of seawater), where i is the second moment of area (moment of inertia) of the free surface about its own centroid, and V is the vessel displacement volume. In practice, FSC values come from the stability booklet for each tank at each sounding level. The corrected GM = GM (solid) - FSC. Free surface effect is worst in wide tanks, least in narrow tanks. Longitudinal subdivisions dramatically reduce FSC because i is proportional to the cube of tank width.
What is the angle of vanishing stability (AVS) and why does it matter?
The angle of vanishing stability (AVS) is the angle of heel at which the GZ righting arm curve crosses zero on the way back down — meaning the vessel has no more righting moment and will capsize if heeled further. A vessel with a large AVS has a wide range of positive stability and is much safer in heavy weather. IMO intact stability criteria require that the range of positive stability extend to at least 30 degrees beyond the angle of maximum GZ. Vessels with AVS below 90 degrees are considered to have limited range of stability. The exam tests your ability to read a GZ curve and identify: the angle of maximum GZ, the area under the curve (dynamic stability), and the AVS.
How does adding or removing weight affect trim?
Trim is the difference between forward draft and aft draft. Adding weight forward of the center of flotation (F) trims the vessel by the head (bow goes down). Adding weight aft of F trims by the stern. The moment to change trim one inch (MCT1" or MCTC in metric) from the stability booklet gives the trim lever. Formula: Change in trim = (weight x distance from F) / MCTC. To calculate individual draft changes: forward draft change = (change in trim x distance from F to forward draft mark) / LBP. Draft marks are read at the forward and aft perpendiculars; the mean draft gives displacement from the hydrostatic tables.
What are the IMDG Code segregation categories for dangerous goods?
The IMDG Code has four segregation categories: (1) Away from — minimum horizontal or vertical separation; (2) Separated from — different compartments or holds, or on deck separated by a full compartment/hold below deck; (3) Separated by a complete compartment or hold from — athwartship or fore-and-aft by a full compartment; (4) Separated longitudinally by an intervening complete compartment or hold from — the most restrictive, requiring full longitudinal separation. The exam tests which class combinations require which segregation level. Explosives (Class 1) require the most restrictive segregation from flammable liquids (Class 3), oxidizers (Class 5.1), and corrosives (Class 8).
What grain stability requirements apply to vessels carrying bulk grain?
Vessels carrying bulk grain must comply with the International Grain Code (SOLAS Chapter VI and Resolution MSC.23(59)). Key requirements: the vessel must have a Document of Authorization for the carriage of grain; the master must have stability data including the assumed grain heeling moments; after loading, the angle of heel due to grain shift must not exceed 12 degrees; the net residual area of the GZ curve between the heel angle and the flooding angle must not be less than 0.075 meter-radians; and the GM must not be less than 0.30 meters. Untrimmed grain (grain not leveled) has higher assumed heeling moments than trimmed grain. These requirements appear on USCG Master exam questions about grain cargo.
What must a cargo securing manual contain?
A Cargo Securing Manual (CSM), required by SOLAS VI/5.6 for vessels of 500 GT and above, must contain: a description of the fixed lashing points, sockets, and container fittings on deck; specifications for all portable securing equipment (lashings, chains, turnbuckles, shackles, twist locks) including safe working loads (SWL); securing arrangements for standard cargo units, containers, and vehicles; guidance on cargo stowage and securing for different sea conditions; and instructions for maintaining and inspecting securing gear. The CSM must be approved by the flag state or a recognized classification society. The USCG exam tests the master's obligation to ensure cargo is secured before departure.
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